Chair

ABSTRACT

The invention relates to a chair, in particular a work or office chair, comprising a seat ( 5 ) mounted onto a chair frame ( 13 ). The front region of said seat can be inclined about a horizontal, pivoting shaft ( 15 ) which is displaced upwards and downwards, following a spatial guide curve in relation to the chair frame ( 13 ). Said seat is also connected in an articulated manner to a rocker ( 7 ) which is directed upwards and extends backwards from an articulated rocker hearing ( 12 ) fixed to the chair frame and which is connected at a distance from the rear edge of the seat, or at the side of said seat ( 5 ). The chair also comprises a backrest ( 4 ) which is attached to the section of the rocker ( 7 ) that is directed upwards, the inclination of said backrest being disproportionately altered, in a forced manner, with the alteration of the inclination of the seat ( 5 ). The invention aims to achieve an increased apex angle between the backrest and the seat, together with a uniform displacement. To achieve this, the backrest ( 4 ) is coupled to the rocker ( 7 ) by means of a coupling point ( 9.1 ) and the seat ( 5 ) is additionally coupled to the backrest ( 4 ) by means of a control lever assembly ( 8, 10 ), which is used to incline the backrest ( 4 ) backwards in relation to the rocker ( 7 ), when the seat ( 5 ) is inclined.

[0001] The invention relates to a chair, in particular a work or office chair, having a seat, which is placed on a chair frame and can be tilted in its front area around a horizontal pivot shaft, which can be moved up and down on a spatial guide curve in relation to the chair frame, and which is hingedly connected to at rocker extending toward the rear from a articulated rocker bearing fixed on the chair frame and is thereafter spaced apart from the seat rear edge, or is laterally guided upward next to the seat, and having a backrest coupled to the upward guided section of the rocker, whose tilt is forcibly changed superproportionally when the tilting of the seat is changed.

[0002] Such an office chair is known from DE 39 16 474 C2. With this known chair, the front end section of a rocker-like pivot lever extending under the seat is tiltably fastened on a bearing bracket of the chair frame, while a section, which is spaced apart from the rear edge of the seat and leads upward, supports the back rest.

[0003] In its front area the seat is placed on a horizontal pivot shaft which, when the seat is tilted toward the rear, is moved together with it downward and backward, while at the same time the backrest is superproportionally tilted toward the rear. With its section extending underneath the seat, the pivot lever is furthermore connected via an intermediate piece with the underside of the seat between the center and rear areas of the latter. In the course of tilting the seat and the backrest, the distance between the rear edge of the seat and the lower edge of the backrest remains substantially the same, so that a so-called shirt-pulling effect is prevented to a large extent. Pressure on the backs of the knees is also avoided, since in the course of the backward tilting of the seat the front of the seat simultaneously moves downward.

[0004] Another chair with a synchronization mechanism between the seat and the backrest is disclosed in DE 87 13 972 U1.

[0005] In connection with such synchronization mechanisms for the simultaneous movement of the seat and the back, applicable specifications cite a transmission ratio in the range between 1.5 and 3.5. With customary chairs of the above mentioned type an opening angle range between the seat and the backrest of 87° to 110°, for example, is achieved. Larger backward tilts, in particular of the backrest, are desired at many work stations, for example air traffic control centers or PC work stations, but cannot be satisfactorily achieved by means of present synchronization mechanisms, because sequence errors occur at larger opening angles, namely too large relative movements between the back and the backrest, so that a shirt-pushing effect occurs, wrong synchronization ratio between the backrest and the seat, increasing distance of the lower backrest area from the pelvis, so that an ergonomically disadvantageous gap occurs because of the pelvis rolling back, and sinking of the lower backrest edge during backward tilt, so that a continuous seat surface is not achieved.

[0006] The object of the invention is based on making available a chair of the type mentioned at the outset, which provides an improved sequence control of the synchronous movement between the seat and the backrest, along with the possibility of larger opening angles, and therefore tilt angles of the backrest toward the back.

[0007] This object is attained by means of the characteristics of claim 1. In accordance therewith it is provided that the backrest is hingedly coupled with the rocker via a coupling point, and that the seat is additionally coupled with the backrest via a control lever arrangement, by means of which the backrest is tilted backward in respect to the rocker when the seat is tilted backward. By means of the articulated coupling of the backrest with the rocker and because of the control lever arrangement, the backrest can be additionally tilted in respect to the rocker in the course of the tilt movement, so that a larger opening angle between the seat and the backrest, along with an even and exactly controllable sequential movement, is achieved. In the course of this, the pelvis is supported by the lower backrest area over the entire course of the tilting, wherein a shirt-pushing effect is prevented even at large angles of tilt and a feeling of pleasant seating is conveyed. An easily attainable opening range lies, for example, between at least 87° to 120°.

[0008] For bringing the seat and the backrest into the active, forward oriented work position a structure is advantageous if the rocker bearing has a torsion rod, which prestresses the rocker against a setting limitation, which limits its tilting position toward the front. An advantageous structure for achieving the synchronization movement at a large opening angle range is furthermore favored in that the control lever arrangement has a lever, which is articulated on the upward guided section of the rocker at a joint location below the coupling point, which is hingedly coupled with an upper lever section via a connecting point with the backrest, and is hingedly coupled with a lower lever section with the rear area of the seat. Furthermore steps, wherein a coupling piece is hingedly connected at a lever connection point of the lower lever section on the one hand, and on the other hand at a seat connection point of the rear area of the seat, also aid in an accurate control, along with a simple construction.

[0009] An advantageous measure for connecting the seat to the lever arrangement consists in a lower seat element projecting past the rear edge of a seat support and the control lever arrangement being connected to the projecting section of the lower seat element. Alternatively, the control lever arrangement can also be connected to the lower seat element underneath or at the side of the seat.

[0010] For example, the placement of the chair backrest for performing the synchronized tilt movement is achieved in a simple manner in that a backrest rocker is provided by means of two articulated connections at the ends for connecting the chair backrest to the upward guided section of the rocker, or that at least one articulated connection is replaced by a thrust linkage.

[0011] A dependable tilted placement of the seat is achieved in that, for connecting the seat with the chair frame, seat rockers are arranged on both sides underneath the front area of the seat, one end of which is hingedly placed on the pivot shaft and the other on the front area of the chair frame, or that a thrust linkage is provided in the frontal seat area. It is particularly advantageous here if the seat rockers are arranged in such a way that their ends facing the pivot shaft move downward when the seat is tilted back.

[0012] The measure by which the seat is connected between its center and rear areas with a connecting piece, or hingedly directly with the rocker, also aids in achieving the synchronous movement.

[0013] A stable placement of the seat and the backrest are aided in that two lateral rocker elements are provided, which are connected with each other by at least one cross brace and whose one, forward projecting section extends at a distance underneath the seat, or laterally thereof, while its upward extending section is arranged spaced apart from the back of the backrest, or laterally thereof. For example, in this case the rocker extends upward in the front lateral seat area and then toward the rear, and can be embodied as an armrest on both sides. In connection with this, the control of the synchronous movement can be achieved in a simple way in that the control lever arrangement extends in an approximately center vertical plane between the two rocker elements and is also spaced apart from the back of the backrest.

[0014] Moreover, an advantageous play-free movement is aided in that a spring force is effective in the pulling direction between the articulated connecting point and the articulated connecting point at the rocker.

[0015] An ergonomically advantageous support of the head is achieved in that a head support is coupled to an extension, which projects past the upper edge of the backrest, of a lever mechanism for the synchronous adjustment of the seat and the backrest, and that the lever mechanism is embodied in such a way that, when the backrest is tilted back, the head support is tilted back over a narrower tilt angle than the backrest. Because of the relative movement between the head support and the backrest, the head is guided forward in the course of increasing tilt, and the neck muscles are relieved, while the field of view is maintained. A simple measure for achieving this consists in that the extension is a rigid or hingedly connected, mechanically controlled extension portion, in particular of the rocker.

[0016] An adjustment possibility for the tilting of the backrest results from the coupling element being length-adjustable.

[0017] The lever can be manually released in that it is connected with the rear area of the seat by means of a manually actuable adjusting element.

[0018] A conventional synchronization mechanism could be realized by removing the coupling rod and locking the backrest joints.

[0019] The invention will be explained in greater detail in what follows by means of an exemplary embodiment, making reference to the drawings. Shown are in:

[0020]FIG. 1, by means of three schematic position representations, a movement sequence in connection with a seat tilt and a backrest tilt synchronized with it,

[0021]FIG. 2, basic position representations of the movement sequence of a synchronized seat and backrest tilt of a chair in accordance with the prior art,

[0022]FIG. 3, an enlarged representation of the seat and the backrest, which are connected by means of a synchronization mechanism,

[0023]FIG. 4, a variation of the synchronization mechanism,

[0024]FIG. 5, a further variation of the synchronization mechanism,

[0025]FIGS. 6 and 7, a lateral representation of an exemplary embodiment of the chair in two different tilted positions of the seat and the backrest,

[0026]FIGS. 8 and 9, two different perspective plan views of a chair in accordance with FIG. 6 or FIG. 7, and

[0027]FIG. 10, three position representations in connection with three different tilted positions of a chair with a synchronization mechanism and a head support.

[0028] Three different seat and backrest tilts in connection with an expanded synchronization mechanism are shown in FIG. 1 by means of three position representations. It can be seen that the backrest 4 can be tilted in relation to the seat 5 over a substantially greater opening range than with a conventional synchronization mechanism, such as represented in FIG. 2 for comparison. The expanded synchronization mechanism is schematically explained in FIG. 3 and shown in various representations by means of an exemplary embodiment in FIGS. 6 to 9.

[0029] The expanded synchronization mechanism has a number of articulated points, in which different lever elements are connected with each other, and the movement of the backrest 4 and the seat 5 takes place around body-related virtual pivot points, so that the spine is supported in an ergonomically advantageous manner during seating. A seat rocker 11, oriented obliquely upward and toward the back, is hingedly connected by its upper section with a pivot shaft 15 on the seat, and by its lower section it is hingedly connected to a protruding section of a bearing block of a chair frame 13. Such seat rockers 11 are provided on both sides of the seat 5. A lower section of a rocker 7 extends from a front rocker bearing 12, which is provided with a torsion rod, past the rear edge of the seat 5 and continues in an upward oriented section on the back of the backrest 4, spaced apart from the latter. The lower part of the rocker 7 is hingedly connected with the seat 5 approximately in its center or its rear half by means of a connecting element 7.1 (see FIGS. 6 and 7) on a lower seat element 5.1. In the end area of the upward extending section, the rocker 7 is connected via a backrest rocker 9, which is hingedly connected at an articulated connection 9.1, with the backrest 4 via a further articulated connection 9.2 of the backrest rocker 9.

[0030] On the lower seat element 5.1 a section is provided, which is extended toward the back past a seat support 5.1, and in its rear area a coupling element 8 in the form of a coupling rod is hingedly connected to a seat connecting point 8.1, while its other end is connected at a lever connection point 8.2 with the lower area of an upward extending lever 10. The latter is hingedly seated at an articulated point 10.1 by means of a coupling member 21 on the upward extending section of the rocker 7, and with an upper section is hingedly attached at a connection point 10.2 to the back of the backrest 4. A spring element 6 in the form of an extension spring is suspended between the articulated connection 9.1 and the connecting point 10.2 for reducing play and for possible force compensation.

[0031] As can be seen in FIGS. 8 and 9, the rocker 7 has two lateral rocker elements, which extend approximately parallel with each other, wherein their distance in the front area of the seat is increased by means of an intermediate section. The two rocker elements 7.2 and 7.3 are connected with each other under the seat by means of a cross brace 7.4, and in the area of the backrest 4 by means of the coupling member 21. The control lever arrangement with the coupling element 8 and the lever 10 is arranged between the two rocker elements 7.2, 7.3 approximately in a vertical center plane.

[0032] An expanded synchronization mechanism is formed by means of the rockers 7 and the control lever arrangement with the lever 10 and the coupling element 8, as well as the respective connections with the seat 5 and the backrest 4 which, in comparison with a conventional synchronization mechanism, results in an enlarged opening angle α, as can be seen by the comparison of FIG. 1 with FIG. 2, which represents the conventional synchronization mechanism. With the instant expanded synchronization mechanism, in the course of a backward tilt the backrest is additionally tilted backward by means of the control lever arrangement in respect to the upward extending section of the rocker 7. At the same time, with a backrest 4 tilted further backward, a relative movement 1 between the back and the backrest 4, a hollow space 2 between the pelvis and the lower area of the backrest, as well as a change in the distance 3 between the rear edge of the backrest 4 and the rear edge of the seat 5 are prevented, so that practically no shirt-pushing effect, rear rolling of the pelvis, or a gap between the backrest and the seat results.

[0033] Besides rotary joints, thrust linkages can also be considered for the movement. For example, in FIG. 5 linear guides 20 are possible in the front area of the seat for placing the seat rocker 11 and instead of the articulated connection 9.2. The synchronization ratio can be affected by means of the length and distance of the levers. It is possible to select spring elements, such as tension, pressure, torsion or gas pressure springs for a suitable weight compensation during seating. A gas pressure spring 16 is shown in FIG. 6.

[0034] A head support 17 can be arranged on an appropriate extension 22 above the upper edge of the backrest 4 which, in the present case, is a one-piece, suitably shaped extension of the rocker 7, as shown in FIG. 10. If the head support 17 is rigidly connected to the rocker 7, a relative movement between the head support 17 and the backrest 4 occurs. With increasing backward tilt, the head support 17 is brought forward and in this way aids the relief of the neck muscles, while preserving the field of view. Because of the relative movement between the head support 17 and the backrest 4, the head is tilted forward by an angle β when the opening angle α is increased. In this way relaxed working is possible even with a large backward tilt.

[0035] Suitable alternatives consist in that no coupling element is provided and the backrest 4 can be separately adjusted, as shown in FIG. 4. The lever 10 can then be separately released by a manual adjustment element 19, for which a gas pressure spring is suitable, for example. The length of the coupling rod 8 can be adjustable, by means of which an adjustment possibility of the backrest tilt is offered. For minimizing the structural space and number of parts it is possible to employ thrust linkages in place of rotary joints. A conventional synchronization mechanism could be realized by removing the coupling element 8 and locking the backrest joints. 

1. A chair, in particular a work or office chair, having a seat (5), which is placed on a chair frame (13) and can be tilted in its front area around a horizontal pivot shaft (15), which can be moved up and down on a spatial guide curve in relation to the chair frame (13), and which is hingedly connected to a rocker (7) extending toward the rear from a articulated rocker bearing (12) fixed on the chair frame and is thereafter spaced apart from the seat rear edge, or is laterally guided upward next to the seat (5), and having a backrest (4) coupled to the upward guided section of the rocker (7), whose tilt is forcibly changed superproportionally when the tilting of the seat (5) is changed, characterized in that the backrest (4) is hingedly coupled with the rocker (7) via a coupling point (9.1), and the seat (5) is additionally coupled with the backrest (4) via a control lever arrangement (8, 10), by means of which the backrest (4) can be tilted backward in respect to the rocker (7) when the seat (5) is tilted backward.
 2. The chair in accordance with claim 1, characterized in that the rocker bearing (12) has a torsion rod, which prestresses the rocker (7) against a setting limitation, which limits its tilting position toward the front.
 3. The chair in accordance with claim 1 or 2, characterized in that the control lever arrangement has a lever (10), which is articulated on the upward guided section of the rocker (7) at a joint location (1O.1) below the coupling point (9.1), which is hingedly coupled by means of an upper lever section via a connecting point with the backrest (4), and is hingedly coupled by means of a lower lever section with the rear area of the seat (5).
 4. The chair in accordance with claim 3, characterized in that a coupling piece (8) is hingedly connected at a lever connection point (8.2) of the lower lever section on the one hand, and on the other hand at a seat connection point (8.1) of the rear area of the seat (5).
 5. The chair in accordance with one of the preceding claims, characterized in that the control lever arrangement (8, 10) is connected in the rear area of the seat (5) to a lower seat element (5.1) underneath or at the side of the seat support (5.2), or a lower seat element (5.1) projects past the rear edge of a seat support (5.2), and the control lever arrangement (8, 10) is connected to the projecting section of the lower seat element (5.1).
 6. The chair in accordance with one of the preceding claims, characterized in that a backrest rocker (9) is provided by means of two articulated connections (9.1, 9.2) at the ends for connecting the chair backrest (4) to the upward guided section of the rocker (7), or at least one articulated connection (9.1, 9.2) is replaced by a thrust linkage (20).
 7. The chair in accordance with one of the preceding claims, characterized in that for connecting the seat (5) with the chair frame (13), seat rockers (11) are arranged on both sides underneath the front area of the seat (5), one end of which is hingedly placed on the pivot shaft (15) and the other on the front area of the chair frame (13), or a thrust linkage (20) is provided in the frontal seat area.
 8. The chair in accordance with one of the preceding claims, characterized in that the seat (5) is connected between its center and rear areas with a connecting piece (7.1), or hingedly directly with the rocker (7).
 9. The chair in accordance with one of the preceding claims, characterized in that two lateral rocker elements (7.2, 7.3) are provided, which are connected with each other by at least one cross brace (7.4, 21) and whose one, forward projecting section extends at a distance underneath the seat (5), or laterally thereof, while its upward extending section is arranged spaced apart from the back of the backrest (4), or laterally thereof.
 10. The chair in accordance with claim 9, characterized in that the control lever arrangement (8, 10) extends in an approximately center vertical plane between the two rocker elements (7.2, 7.3) and also spaced apart from the back of the backrest (4).
 11. The chair in accordance with one of claims 6 to 10, characterized in that a spring force is effective in the pulling direction between the articulated connecting point (10.2) and the articulated connecting point (9.1) at the rocker.
 12. The chair in accordance with one of the preceding claims, characterized in that a head support (17) is coupled to an extension (22), which projects past the upper edge of the backrest (4), of a lever mechanism for the synchronous adjustment of the seat (5) and the backrest (4), and the lever mechanism is embodied in such a way that, when the backrest (4) is tilted back, the head support (17) is tilted back over a narrower tilt angle than the backrest.
 13. The chair in accordance with claim 12, characterized in that the extension (22) is a rigid or a hingedly connected, mechanically controlled extension portion, in particular a rocker (7).
 14. The chair in accordance with one of claims 4 to 13, characterized in that the length of the coupling piece (8) can be changed.
 15. The chair in accordance with one of claims 3 or 5 to 13, characterized in that the lever (10) is connected with the rear area of the seat (5) by means of a manually actuable adjusting element (19). 